1. Field of the Invention
This invention relates to an improvement in an air disinfection apparatus, and more particularly to an improved apparatus for the disruption of power to a source of radiation, typically a radiation lamp that generates ultraviolet light, when the active radiation source is removed from a confined space, for example, a HVAC (“heating/ventilation air conditioning”) duct. The invention further relates to an air disinfection module that incorporates such an apparatus within a HVAC, and a method for guaranteeing disruption of power to a radiation source when the active radiation source is removed from a confined space.
2. Related Art
Germicidal lamps that generate ultraviolet light are now being used in HVAC duct systems for the disinfection of bacteria transported with the air. The germicidal or ultraviolet (hereinafter “UV”) lamps employed in HVAC ducts are generally powered by a source of electricity commonly located externally of the duct. The removal of the lamp(s) from the HVAC duct, however, presents a safety problem in that the UV lamp's power may not be discontinued during its removal, e.g., by disconnecting a plug from a wall socket or by disconnecting the lamp's electrical connection with a ballast. The prolonged exposure to the ultraviolet radiation emitted from the lamp, along with the lamp's intensity, may cause serious injury to the eyes or touch if precautions are not taken to shut the lamp down before its handling or removal from the HVAC duct. In addition, the efficiency for generating ultraviolet light by a UV radiation lamp varies widely depending on the operating environment that the lamp is subject to, e.g., the temperature variations in a HVAC duct due to the cooling of the air passing through the duct during the warmer months of the year, and heated duct air during the winter months. It therefore becomes desirable to provide a safety mechanism that assures the disconnection of a radiation lamp before its removal from a duct. It is also desirable to maintain an operating environment for the lamp that will enable it to perform at peak efficiency with maximum longevity.
An apparatus for sterilizing air using ultraviolet radiation emitting probes inserted into an air duct is generally described in U.S. Pat. No. 5,742,063 issued to Scroggins et al. on 21 Apr. 1998. Various lamp socket configurations have also been disclosed in the prior art. For example, FIGS. 5 and 6 of U.S. Pat. No. 2,472,977 issued to Mageoch et al. on 14 Jun. 1949, disclose a fluorescent lamp socket formed of a body member 13 that has a cylindrical recess 18 and a collar 29 that fits over an opening 35 within a supporting panel 36 of a fluorescent light fixture. The body member 13 has external mounting flanges 15 for mounting to collar 29 and panel 36. In order to insure proper registry of body member 13 and collar 29, the collar is provided with an axially extending cup-shaped projection 31 adapted to nest in the annular seat 17 of the cylindrical recess 18 of body member 13. The body member 13 and collar 29 are permanently secured to the supporting panel 36 by rivets 32.
FIG. 6 of U.S. Pat. No. 5,902,552 issued to Brickley on 11 May 1999, illustrates an ultraviolet air sterilization device 10 containing a housing unit 12 and one or more internally threaded conduit mounting flanges 16 connected to germicidal lamps that protrude into the air stream of an air handling duct 11. Receptacles 30 are constructed of a UL approved plastic material with external threads 32 for engagement with mounting flanges 16. Each receptacle has an opening 34 for receiving a transfer cable 50 containing wires 53 which are connected to pins 26 on base 22 of lighting element 24. A grounded power supply plug 40 with cord 42 is used to provide power to the sterilization device 10 via a ballast. Power is transferred from the ballast through transfer cables 46 to transfer cables 50 of the receptacle 30. FIG. 6 of U.S. Pat. No. 5,968,455 issued to Brickley on 19 Oct. 1999 illustrates a similar arrangement.
U.S. Pat. No. 5,866,076 issued to Fencl et al. on 2 Feb. 1999, discloses an ultraviolet lamp comprising a tube and a fixture for supporting the tube at one end only, the fixture being mounted on the inside or outside of a single wall of a HVAC duct. As shown in FIG. 3, the fixture has a stem 135 into which the tube is inserted and a ring 131 about the stem. A mounting mechanism in the form of a spring clamp 510 is biased against the ring 131 for holding the stem 135 in place. A gasket 400 is interposed between the ring 131 and wall 210 of fixture 200 to act as a shock absorber and vibration damper.
Disclosures of more complex sockets for “twin tube” fluorescent lamps sharing a common base are contained in U.S. Pat. No. 4,799,896 issued to Gaynor et al. on 24 Jan. 1989.